ATI's Nvidia-slaying Radeon HD 4870 X2, previewed last month, will get official tomorrow at SIGGRAPH says the WSJ, who notes that some reviewers are calling it the most powerful card around. It's an interesting test of ATI's graphics card strategy: Cheaper, less power-hungry GPUs that can be easily strapped together (like the dual-GPU 4870 X2) versus Nvidia's penchant for obscenely powerful single GPUs. The best part? Whoever you go with, you can't really go wrong anymore. Update: The reviews are rolling, and yes, the $549 HD 4870 X2 destroys everything else. [WSJ]